Manually hand operated adjustable wrenches having variable jaw adjustment within a range, for use with a particular size fastener are old in the art. The most traditional type is typically called a crescent wrench. The design of a crescent wrench includes a movable jaw slide and a guide track that is opposed to a fixed jaw, wherein the movable jaw is adjusted by means of a worm gear that is supported within the housing that forms an end portion of the adjustable wrench handle. Typically, the worm gear functions as a thumb wheel, wherein rotating the worm gear causes the jaw to move toward and away from the fixed jaw. One issue with the crescent wrench is the speed of adjustment that is attainable, thus to have a higher speed of adjustment with the worm gear and thumb wheel would require a steeper helical angle to be constructed for the cut of the worm gear, however, this steeper angle decreases the ability of the movable jaw to reliably hold a secure position upon the fastener, especially when the fastener is under a high level of force as against movable jaw, in effect causing the worm gear to rotate in a manner to loosen or in other words drive the two jaw faces apart. This results in causing the problem of rounding off of the fastener points which is undesirable and can also cause injury to the user's hand, in that as the wrench slips around the points of the fastener while the user is applying force to the end of the handle furthest from the jaws can result in scraped and cut knuckles. As a practical matter, the steepness of the helical angle of the thumb driven worm gear is about 30 degrees off of a perpendicular axis of rotation for the worm gear.
Another drawback of the typical traditional crescent wrench, is that in order to adjust the jaws relative to one another the user's hand must move from its advantageous position on the handle which is at the furthest distance from the jaw portion of the handle that results in maximum torque applied from the force of the user's hand, wherein the users hand to adjust the jaws relative to one another must be moved toward the jaw portion of the handle for the user's fingers to engage the worm gear to facilitate jaw adjustment. This requirement of the user having to move their hand on the handle of the wrench can be especially inconvenient when the wrench is being used in a tight or confined space around the fastener. Thus, the aforementioned description of a typical crescent wrench has identified three major problems, the first problem being the slow speed of adjustment between the jaws, the second problem being the inconvenience of the user having to reposition their hand on the handle to make the jaw adjustment, and the third problem being the lack of a secure holding of a position of the movable jaw especially while under load from the function of tightening or loosening the fastener causing not only damage to the fastener itself but also potential injury to the user's hand. These three problems have been well recognized in the prior art and the following is a partial summary of some of the solutions that have been put forward in the prior art of manually hand operated adjustable wrenches. One type of adjustable wrench in the prior art utilizes a serrated tooth rack, wherein a pair of separated tooth racks matably engage with one rack on the movable jaw segment and another rack on a spring loaded plunger, wherein the spring urges the racks to matably engage thus securing the movable jaw segment in a particular position relative to the fixed jaw segment. To move the movable jaw segment the plunger is manually pulled back against its urging to disengage the tooth racks, thus allowing the movable jaw segment to freely move.
One example is given in U.S. Pat. No. 1,501,214 to Garrison that discloses a sliding jaw wrench wherein the lower jaw is movable and lockable against an acute angle serrated tooth rack interface with a mating serrated rod or plunger. In Garrison the rod is selectively manually moved by a thumb piece to allow free adjustment of the movable jaw segment, and when in use the user must manually close the immovable jaw segment against the fastener and then simultaneously release the rod for the serrated toothed rack interface to engage thus locking the movable jaw in a secure position. Although Garrison overcomes the problem of the movable jaw not being securely locked in position by virtue of the toothed rack interface, there is a problem in that the movable jaw must be manually positioned by the user's second hand as against the fastener while the users first hand must manually hold the rod away from the movable jaw segment at the same time, this can be especially difficult in tight or confined areas around the fastener. Another prior art example is in U.S. Pat. No. 2,724,301 to Parent et al. that discloses a sliding jaw wrench wherein the lower jaw is movable and lockable against an acute angle serrated rack interface with a mating serrated block that has a rack interface similar to Garrison in structure and function, with the exception that the block axially slides on a pin transverse to the jaw faces.
Also, U.S. Pat. No. 5,152,198 to Schmitz, Jr., disclosed is a snap lock adjustable wrench that utilizes a spring to urge the movable jaw closed and is otherwise similar to Garrison in having an acute angle serrated rack interface between the jaw and the rod, one additional feature is an axially locking threaded knob on the rod to compress the serrated rack interface. Again, U.S. Pat. No. 1,523,093 to Wilcox, disclosed is an adjustable sliding jaw wrench that is similar to Garrison in structure and function with the exception of the spring loaded rod being shorter and having two sandwich plates that have their respective serrated racks offset or staggered which is to allow a finer adjustment of the movable jaw. Further, in U.S. Pat. No. 1,053,181 to Iring, disclosed is an adjustable wrench utilizing a movable lower jaw with a serrated rack, however, being matably engaged with a parallel positioned serrated rack bar that is mounted on a spring loaded pivot, thus the bar must be manually disengaged by one hand while the movable jaw is selectably positioned by the other hand as in the other prior art examples given in this paragraph. A final prior art example in this area is in U.S. Pat. No. 1,397,214 to Hose the discloses a wrench with a mating acute angle serrated rack similar to Wilcox except for the spring loaded rod not being two pieces and the rack being inclined slightly with the stated purpose to allow for a more firm engagement of the mating rack when the jaws are loaded from tightening or loosening of the fastener, in addition the incline acts to allow easier sliding of the mating racks for pushing the movable jaw closed with set screws that can further hold the rod axially.
None of the aforementioned prior examples address the problem of the speed with which the movable jaw can be placed into its selected position and all require the use of two hands to both manually disengage the rod serrated tooth interface from the movable jaw serrated tooth interface and at the same time requiring the user to manually move the movable jaw into the selected position, consuming both of the user's hands at the same time and causing difficulty where there is a tight or confined space around the fastener.
Other prior art approaches to the manually adjustable wrench have a higher degree of complexity such as in U.S. Patent Application Publication No. U.S. 2002/0112574 A1 to Marks that discloses a slide switch adjustable wrench, allowing through a mechanical linkage adjustment of the movable jaw from the handle portion opposite of the jaw portion thus overcoming the two hands required problem as previously discussed and assisting in the speed of adjustment issue of the movable jaw, however, as Marks still uses the helical thumb wheel to adjust the movable jaw there's still the aforementioned issue of the movable jaw not being secured in a selected position as against the fastener. Another solution is given in U.S. Pat. No. 5,375,490 to Carlmark that utilizes an adjustable spanner having a crescent gear segment meshed with a toothed rack on the movable jaw with the disadvantage being, of having to initiate a separate locking device to fix the movable jaw position.
Also, in U.S. Pat. No. 4,454,791 to Seward, III utilized is a geared thumb wheel that mates with a rack gear on the movable jaw, being similar to Carlmark in requiring a separate selectable lock to engage the rack gear of the movable jaw to secure the movable jaw's position. Further, in U.S. Pat. No. 3,803,954 to Lenker, a pivoted handle is used having a pinion that engages the toothed rack movable jaw not having any auxiliary device for locking the movable jaw into a selected position other than the force exerted on the pinion that is that the end portion of the handle upon the movable jaw rack. Finally, in U.S. Pat. No. 1,317,546 to Bryant disclosed is an adjustable wrench with a spring loaded thumb pivot that engages and disengages a serrated rack from a slide bolt for locking the movable jaw into a spring loaded position from a lever with the thumb pivot also acting to open the movable jaw by an arm against the lever when the slide bolt is disengaged from the serrated rack operating through a complex linkage, which does allow one-handed operation for setting and locking the movable jaw, however, the adjustable wrench must be held near the jaw portion and not the handle end portion that opposes the jaw for proper and efficient use as previously described.
What is needed is an adjustable wrench for manual use that only requires one hand operation from the user with the user's hand positioned in its normal location on the wrench handle which is on the end portion opposite of the wrench jaw portion, thus to allow the wrench jaws to be positioned in tight or confined spaces around the fastener and for a way to quickly and easily set the movable jaw into the selected position and have the movable jaw securely locked into the selected position, thus having the added benefit of one handed ratcheting of the fastener.